Re: Xen 4.3 release planning proposal

[Dan Magenheimer <dan.magenheimer@oracle.com>]

> From: Jan Beulich [mailto:JBeulich@suse.com]
> Sent: Friday, August 31, 2012 5:01 AM
> To: Dan Magenheimer
> Cc: David Vrabel; George Dunlap; xen-devel@lists.xen.org
> Subject: Re: [Xen-devel] Xen 4.3 release planning proposal
> 
> >>> On 30.08.12 at 18:11, Dan Magenheimer <dan.magenheimer@oracle.com> wrote:
> > Of course, 18 months is far too long a release cycle for this approach,
> > and 9 months may be too long as well.  I think a target cycle
> > of 6 months with a "window" of 6 weeks would be a step in
> > the right direction
> 
> I disagree. Even the fix months of a freeze we're having right
> now already is way too long. Nor do I personally consider the
> two-weeks-out-of-ten (approximately) model on the Linux side
> too nice. Having larger development windows, and shorter
> stabilization periods is pretty desirable imo, the more on Xen
> where, despite its name, -unstable really normally isn't that
> unstable.

I apparently still haven't made my point clear.

With the current Xen model, there is a functionality freeze for
MONTHS during the rc cycles.  This guarantees a stampede
when the freeze ends, which almost certainly guarantees a long
period of instability in xen-unstable.  I agree that "-unstable
really isn't that unstable" but IMHO that's mostly because of the
very long release cycle.

With the Linux model, the stampede still occurs but it gets
sorted out in linux-next and the cream that rises to the top
is merged into the next release at the next (brief) window.

(Did you know that Linus now mostly refuses any new functionality
that wasn't already in linux-next at least for a week or so
before the window?)

So on Linux the "development window" is 100% _minus_ "the window",
i.e. the stabilization period and the "development window"
happen concurrently and the only time new functionality cannot
be taken is during the "window" (during which linux-next is
unavailable).

While the root cause of the difference between Xen and Linux
release cycles may indeed be that Linux has more developers,
I think everyone agrees the current Xen model (18 months since
last release) is broken, so it may be worth re-examining the
process rather than just saying "we'll try to do better this
time and maybe get it down to 9 months"... even though that
was the goal last time and it didn't work.  See classic
definition of insanity.

Just my opinion though...